Single-in-line packages (SIP's) are well known in the electronics art, particularly the semiconductor art. SIP's are an electronic device or circuit package style which have a single row of generally flat leads protruding from one edge. The flat leads usually lie in the same plane. The SIP package may contain one or more electronic elements, as for example, semiconductor devices or integrated circuits.
It is frequently desired to provide a heat spreader fin protruding from the package that aids in removal of heat from the internally mounted chips. In the prior art, this heat spreader has usually been formed by extending the portion of the leadframe on which one or more of the electronic elements are mounted so as to protrude from the package body. A SIP having an externally protruding heat spreader is described for example in U.S. Pat. No. 4095253 which is incorporated herein by reference. A difficulty with this and other prior art SIP devices is that the semiconductor or IC die, for example, is directly bonded to this heat spreader. The heat spreader then has the same electrical potential as the die or IC substrate. This is often undesirable.
Electrically isolated heat spreaders can be obtained by providing an insulating material, e.g., alumina or beryllia, between the die and die bond portion of the heat spreader. However, this has a number of disadvantages well known on the art. Among these are the high cost of such materials and the additional manufacturing steps needed to mount them on the heatspreader and then mount the die thereon.
Accordingly, it is an object of the present invention to provide a means and method for improved heat removal from SIP type devices where the externally protruding heat spreader is electrically isolated from one or more of the electronic elements within the SIP. It is a further object of the present invention to provide the above-noted advantages and objects without use of insulators between the electronic elements and the die bond portion of the leadframe on which they are mounted. It is an additional object to provide the above-noted advantages and objectives more simply and at lower cost than in the prior art.